The present invention relates generally to a process and apparatus for the alkaline stabilization of sludge.
In particular, the present invention relates to a process and apparatus for the treatment of substantially liquid sludge with an alkaline additive to reduce pathogens and vector attractiveness. A useful end product is provided that will allow beneficial re-use of sludge, such as enabling the sludge to be applied to land on which crops may be grown. The invention includes a unique method and apparatus for adding an alkaline additive to substantially liquid sludge to raise the pH of the resulting mixture to a predetermined level for a predetermined period of time to neutralize pathogens and reduce vector attractiveness (rats, mice, and flies).
Under the relevant Environmental Protection Agency Regulations, to reduce the pathogens in the sludge to the required level, a pH level above 12 must be maintained for at least two hours. Additionally, to reduce the vector attractiveness in the sludge to the required level, a pH level of at least 11.5 must be maintained for at least 22 hours.
Prior to the present invention, when an alkaline additive, such as lime, was put into a basin, it often settled to the bottom of the tank, and a sufficient pH level was not reached due to inadequate methods of adding the alkaline additive to the basin containing the sludge.